The present invention relates to fluorine-containing copolymers derived from at least one fluorinated olefin, at least one polycyclic ethylenically unsaturated polycyclic monomer with a fused 4-membered ring, and, optionally, other components. The polymers are useful for photoimaging compositions and, in particular, photoresist compositions (positive-working and/or negative-working) for imaging in the production of semiconductor devices. The polymers are especially useful in photoresist compositions having high UV transparency (particularly at short wavelengths, e.g., 157 nm) which are useful as base resins in resists and potentially in many other applications.
There is a critical need for resist compositions for use at 193 nm, and particularly at 157 nm, or lower that have not only high transparency at these short wavelengths but also suitable other key properties, including good plasma etch resistance and adhesive properties.